Yi Mao, MIT Collaborators: Max Tegmark, Alan Guth, Matias Zaldarriaga, Matt McQuinn, Oliver Zahn, Tom Faulkner, Ted Bunn, Serkan Cabi Constraining cosmological

Yi Mao, MITCollaborators: Max Tegmark, Alan Guth,

Matias Zaldarriaga, Matt McQuinn, Oliver Zahn, Tom Faulkner, Ted Bunn, Serkan Cabi

Constraining cosmological and gravitational parameters with upcoming astrophysical data

What do we learn in cosmology?

Yi MaoFermilab seminarJanuary 23, 2008

0th order:Expansion

a(t)k

H(z)


Distant light is {dimmed

redshifteddistance Vs. z H(z)

1st order:Clustering

Cl, P(k), …


CMBZ ~ 1089

Galaxy surveys

z 1Supernovae IaGravitational Lensing Ly-a forest

But the best is yet

to comePrecision CMB (polarization, small scales), precision lensing ……

and 21cm tomography


CMBZ ~ 1089

Galaxy surveys

z 1Supernovae IaGravitational Lensing Ly-a forest

21cmtomography

Yi Mao

Fermilab seminarJanuary 23, 2008

Murchison Widefield Array (MWA)• Located in western Australia • 500 antennas; array diameters 1500m; • Measures z=6~12

Murchison Widefield Array (MWA)• Located in western Australia • 500 antennas; array diameters 1500m; • Measures z=6~12

Yi Mao


Other arrays• Square Kilometre Array (SKA)• Low Frequency Array (LOFAR)• 21cm Array (21CMA)

• Square Kilometre Array (SKA)• Low Frequency Array (LOFAR)• 21cm Array (21CMA)

21cm line from the Epoch of

Reionization


QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

Yi Mao


21cm Power spectrum21cm Power spectrum

• 21cm power spectrum is not isotropic because of redshift space distortion!

• 21cm power spectrum is not isotropic because of redshift space distortion!

How accurately can 21cm tomography

constrain cosmological parameters?


Yi Mao


Yi Mao


YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)

K

Yi Mao



K

Ionization power spectrum modeling


Yi Mao


OPT

Yi Mao


PESS

Yi Mao

Fermilab seminarJanuary 23, 2008 YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)

MID

Yi Mao



K

Optimal array configuration


Yi Mao


LOFAR MWA SKA

MID

OP

T

Size of compact core

Siz

e of

tot

al in

ner

core


Size of compact core

Siz

e of

tot

al in

ner

core

MWA in OPT model



Future: 3D neutral hydrogen maps?


Testing gravity in a general framework


Generalize PPN

• A general geometry is determined by metric (g) and connection (), both independent of each other.

• Three quantities characterize the departure from Minkowski spacetime:


Gen

eral

ized

geo

met

ry f

amily

tre

e

Constraining torsion


Parametrization of torsion around Earth

to linear order in m and a

Constraining torsion with GPB

Image from http://einstein.stanford.edu

Constraining torsion with GPB

YM, Tegmark, Guth, Cabi (2006)

Constraining f(R) gravity


Yi Mao


Solar system constraints on f(R) Chameleon

Faulkner, Tegmark, Bunn and YM (2007)

Yi Mao


Constraints on cubic f(R) model

Faulkner, Tegmark, Bunn and YM (2007)

Yi Mao


Outlook

• 3D HI mapping: direct view into the dark ages, precision constraints on cosmological parameters

• Better understanding of the Epoch of Reionization• New tests of Einstein gravity on scales from the solar

system to the cosmos• Common question for cosmology and gravitation: Dark energy = cosmological constant or modified gravity? Dark matter = new particles or TeVeS/MOND? Can GR (and standard cosmological model) be further

tested?

Tegmark & Zaldarridaga, astro-ph/0207047+updatesYi Mao


Yi Mao


21cm line21cm line

•

• Spin temperature , where

• Emission if Ts > Tcmb; absorption if Ts < Tcmb• Saturated when Ts >> Tcmb; arbitrarily large when Ts << Tcmb• The last factor makes the anisotropy!

•

• Spin temperature , where

• Emission if Ts > Tcmb; absorption if Ts < Tcmb• Saturated when Ts >> Tcmb; arbitrarily large when Ts << Tcmb• The last factor makes the anisotropy!

Yi Mao


Ts couplingsTs couplings

• Absorption of CMB photons and stimulated emission

• Collisions with H, e, p: Ts Tk

• Scattering of UV photons( the Wouthuysen-Field Effect): Ts TLya

• Absorption of CMB photons and stimulated emission

• Collisions with H, e, p: Ts Tk

• Scattering of UV photons( the Wouthuysen-Field Effect): Ts TLya

Furlanetto, Oh & Briggs 2006

Yi Mao


• zdec~150: compton heating.

Tk = Tcmb before zdec; Tk~(1+z)2 after.

• Z1: Ts = Tk before z1; Ts Tcmb after.

• Zh: IGM Tk > Tcmb.

• Zc: Wouthuysen-Field Effect couples Ts = Tk again.

• Zr: reionization.

• zdec~150: compton heating.

Tk = Tcmb before zdec; Tk~(1+z)2 after.

• Z1: Ts = Tk before z1; Ts Tcmb after.

• Zh: IGM Tk > Tcmb.

• Zc: Wouthuysen-Field Effect couples Ts = Tk again.

• Zr: reionization.

Thermal histroy of IGMThermal histroy of IGM

Documents

Yi Mao, MIT Collaborators: Max Tegmark, Alan Guth, Matias Zaldarriaga, Matt McQuinn, Oliver Zahn, Tom Faulkner, Ted Bunn, Serkan Cabi Constraining cosmological